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TRAVERSNG AND LEVELING HEAD FR THEODOLITBS. No. 561,876.I

Patented June 9, 1896.

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ANDREW BLRMMHPHUTOMTHDWASMNGTOKDC.

lJNiTED STATES PATENT rrrcE,

YVILLIAMA GEORGE ENTVISTLE, OF BROKLYN, NEWT ZEALAND, ASSIGNOR TO ALEXANDER IRGNSIDE LlTTLEJOIIN AND PETER TON, NElV ZEALAND.

STILL, OF VELLING- SPECIFICATION forming part of Letters Patent No. 561,876, dated June 9, 1896. Application iileil January 25,1896. Serial No. 576,871. (No model.) Patented in New Zealand June l1, 1895, No. 7,665.

To a-ZZ whom it may concern/.-

Be it known that I, WILLIAM GEORGE EN- TWISTLE, a subject of the Queen of Great Britain, residing at Brooklyn, in the provincial district of Vellington, in the Colony of New Zealand, have invented certain new and useful Improvements in Traversin g and Levcling Ileads for Theodolites or other Instruments, (for which Letters Patent have been granted to me in New Zealand, No. 7 ,665, under date of June Il, 1395;) and I doliereby declare that the following is a full, clear, and exact description of my invention, such as will, enable others skilled in the art to which it appertains to make and use the saine.

rlhe object of my invention is to provide a new and simple method of combining and clamping together the traversin g and levelin g parts of a theodolite or similar instrument at ter the machine has been set and of readily releasing the same for another operation.

My invention is illustrated on the accompanying sheet of drawings, on which- Iiignrc 1 is-a sectional view of myimproved head as used for theodolites and similar instruments. Fig.` 2 is an elevation of part of the same when set to an angle and moved on the traverse-plate to its full extent. Fig. 3 is a plan showing the traversing plate, and Fig. e is a sectional view through the line l 2 on Fig. l.

Similar letters indicate like parts in all the figures.

A are the ordinary legs or supports, which are joined to the cap-piece a, by pins A' rlhis cap-piece a is formed with a lower dan ge a' and an upper flange a2, joined together by distance-pieces a3, so as to leave a free space in which the traversing plate b may move freely in all directions horizontally.

c is the traversing head, having a spherical upper surface c and flat base ci, so that it can be traversed horizontally by the hand When desired simultaneously with the plate h.

d is the leveling-head, fitted with the crdinary screw d. for receiving the theodolite, which screw is covered by a cap e when the instrument is not in use. This leveling-head d has a base d?, hollowcd out internally in the form ot' a sphere, so as to :fit and move freely upon the spherical surface c' ol the travers` ing head, and also has a projection-piece d?, fitted With a left-handed screw di, for a purpose to be hereinafter described. The cap e is iitted with a square recess e', which forms a Wrench for turning the joint-screws A.

By this description of the parts it will be scen that an instrument screwed on at d can be made to slidein any direction horizontally upon the base c2 and can be set to ahorizontal position or to an angle by being adjusted on the spherical surfacerc. Such motions have been applied to theodolites and similar instruments, and I lay no claim to the means which allow of such movements, my invention consisting of the improved method of clamping the whole of the parts together, and Which I will now proceed to describe.

p is the clamping-piece, havin g at its lower end a semispherical projection p', bored accurately to receive the plumb-line q, the center of the semisphere being at p2, which center is also the center from which is described the spherical surface c'. This projection p Works accurately in a spherical hollow h formed in the traversing plate b to receive it.

The upper end of the clamping-piece p is formed in the shape of the capstan-head p3, having an internal thread p4 screwing onto the thread d* of the levelinghead d, and around this capstan-head are holes p5.

r is a ring litting loosely around the levelin g-head d and iitted with tWo projections r, which have internal threads to receive the screws s, the ends of which s' project into the holes p5 of the capstan-head and serve to turn the said capstan -head when the ring fr is turned.

It Will be seen from this description of the several parts and by reference to the drawings that the ring r being turned from left to right the capstan-head p is also turned, and by this action, d* being a left-handed screw, the lcvelinghead d is drawn down tight upon the traversing head o and the traversing plate b is drawn up against the plate or iiangc a2, so that both leveling-head and traversing head are irmly fixed by one action oi the hand acting on the projecting pieces r', and this takes place in Whatever position the lev- ICO eling-hea'd Or traversing head may have as-` sumed. Of course, On moving the ring '1' back from right to left the whole is again loosened ready for resetting. The point p2 being the center of the spherical traversing head c, the plumb-line q is not materially affected bythe movement of the traversing head, but only by the horizontal movement of the plate a.

I Claim as my inventionl. In a traversing and leveling head for theodolites and other similar instruments a clamping-piece p having a eapstan-head p3 acting upon the leveling-head d by means Of the sorew d4, and having a tailpieee 19 carrying the plumb-line q and Oscillating or revolvin g in a traversing plate h as and for the 

